الفهرس 
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Abstract
In the present study a total of 60 Streptococcus pneumoniae isolates
were recovered from 178 sputum samples, they were collected from chest
infected patients attending Mansoura Chest Hospital during the period from
January 2016 to February 2017. The identification was based on colony, cell
morphology and biochemical tests. The scanning electron microscopy
revealed that all isolates were capsulated but do not show pilus in any of
these isolates.
Genotypic characterization was achieved by detecting some virulence
genes using PCR technique. All sixty isolates harbor autolysin mediated
gene (lytA). On the other hand, fifty-five (91.6%) and 13 (21.6%) of the
isolates were positive for pneumolysin mediated gene (ply) and gene
encoding pilus protein (rrgA) respectively.
The ability of the tested isolates to form biofilm was tested by
microtitration plate technique. Strong biofilm formation was observed in
21.67% of the recovered isolates. Moderate to weak biofilm formation were
observed in 45% and 25% of the isolates respectively. In contrast, 8.33%
were none producer.
The susceptibility of tested isolates to 20 different antimicrobial agents
was performed using disk diffusion method. Data obtained revealed that,
resistance rate in respect to β-lactam antibiotics was ranged from 78.33% to
66.66%, penicillins and cefaclor were least effective antibiotics. However,
cefoperazone and cefotaxime were most effective antibiotics. In respect to
non β-lactam antibiotics; the resistance rate was ranged from 53.3% to 35%.
Erythromycin, rifampicin, tetracycline, co-trimoxazole were least effective
antibiotics, while linezolid and clindamycin were most effective antibiotics.
Most of isolates (93%) were multidrug-resistant (MDR) and had a high
MAR index value (>0.2).
Using a multiplex PCR, the penicillin binding protein genes pbp1a,
pbp2b and pbp2x were found in 33 (55%), 25 (41.7%) and 45 (75%) of the
isolates, respectively. All isolates were contained at least one penicillin
binding protein resistant gene. Thirty-two (53.3%) of isolates showed two
resistance genes; pbp1a and pbp2x. Ten isolates (16.7%) showed the three
resistance genes; pbp1a, pbp2b and pbp2x.